Reversing alarm



FIG. 1 is a front elevation view of my new design for a reversing alarm;

FIG 2 is a rear elevation view thereof;

FIG 3 is a left side elevation view thereof;

FIG 4 is a right side elevation view thereof;

FIG 5 is a top plan view thereof; and,

FIG 6 is a bottom plan view thereof.

The broken lines shown in FIG. 3 form no part of the claimed design. 

The ornamental design for a reversing alarm, as shown and described. 